Correlation of trans-cerebellar diameter by ultrasonography and gestational age in third trimester

Background: Accurate gestational dating is essential to any assessment of pregnancy, fetal development, and neonatal care. This study aimed to determine the accuracy of trans-cerebellar diameter in predicting gestational age during third trimester of pregnancy. Methods: This prospective observational study included 250 pregnant women with singleton pregnancies underwent routine ultrasound examination in third trimester. Results: This study established reference values for four fetal dimensions bi-parietal diameter (BPD), femur length (FL), abdominal circumference (AC), and trans-cerebellar diameter (TCD) across gestational ages in the third trimester. The BPD increased from 77.1 mm at 28 weeks to 103.5 mm at 40 weeks, FL from 50.7 mm to 72.9 mm, AC from 232.1 mm to 346.4 mm, and TCD from 30.1 mm to 42.6 mm during the same period, with all showing statistically significant differences (p